Tracerlab TGC-1 and TGC-2 End Window GM Tubes
The TGC-1 and TGC-2 are glass walled end window GM tubes designed for beta counting. They were the first GM tubes produced by Tracerlab, Inc. The earliest references I have for them are June 1948, while the last reference is 1958. TGC, as might be expected, stands for Tracerlab Geiger Counter.
The key difference between the two tubes is that the TGC-1 has a 3-4 mg/cm2 mica window while the window of the TGC-2 is < 2 mg/cm2. Due to its thinner window, the TGC-2 was capable of alpha detection and had a better efficiency for low energy betas. Both employed helium as the fill gas together with an organic quench gas.
Size: 3.75” long and 1.5” inner diameter
Window Thickness: TGC-1 3 – 4 mg/cm2
TGC-2 ca. 1.5 mg/cm2
Wall: glass, > 300 mg/cm2, aquadagged on inside
Anode: Tungsten central wire.
Operating voltage: 1400 V
Plateau length: 300 volts
Fill gas: helium
Fill gas pressure: 720 mm Hg
Dead time: ca. 200 us
Base: four prong ceramic base:
Price: TGC-1 $50 in 1948, $43.50 in 1952
TGC-2 $75 in 1948, $53.50 in 1952
June 1948 p 80
June 1948 p 103
Instrument Catalog, page date
Tracerlab Inc, Catalog E, March 1958
Last updated: 07/25/07
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